GI TBL 24

Question 1

What makes up the musculotendinous sheet of the ANTEROlateral wall?

Answer 1

3 lateral muscle layers and their anterior aponeuroses.

The three flat muscles are the internal and external oblique and transverse abdominis (superficial to deep layer)

Question 2

What cells (embryological derivative) form the musculotendinous sheet?

Answer 2

myoblasts and fibroblasts of the parietal mesoderm form the sheet.

Question 3

Discuss the external oblique- layer formation, fiber orientation, origin/attachment.

Answer 3

superficial muscle layer

fibers run inferomedially from the inferior six ribs (5th-12th ribs) to the iliac crest.

Question 4

Discuss the internal oblique- layer formation, fiber orientation, origin/attachment.

Answer 4

intermediate muscle layer

fibers run superomedially from the iliac crest to the inferior three ribs (10th-12th ribs).

Question 5

Discuss the shared actions of the EXTERNAL oblique and ipsilateral/contralateral internal/external oblique. How are the shared actions accomplished?

Answer 5

external oblique and contralateral internal oblique form a two-bellied muscle sharing a common central aponeurosis

synergistic actions of the muscle bellies cause flexion and rotation for torsional movement of the trunk.

Question 6

What muscle forms the innermost muscle layer of the abdominal wall?

Discuss said muscle fiber orientation, origin, insertion, and action.

Answer 6

Transverse abdominis

Contraction of its fibers, which run transversely from the iliac crest and internal surfaces of the inferior six ribs (7th-12th ribs) to the linea alba, increases intraabdominal pressure.

Question 7

What forms the rectus sheath and what does it enclose?

The rectus sheath fuses in the midline to form _____.

Answer 7

the fused aponeuroses of the three muscle layers form the rectus sheath, which encloses the paired rectus abdominis muscles and fuses in the midline to form the linea alba.

Question 8

What is the surgical relevance of the linea alba?

Answer 8

the linea alba is used for rapid midline incisions that are relatively bloodless and avoid major nerves.

Question 9

Discuss the fiber orientation of the rectus abdominis, origin, attachment, and action.

Answer 9

the rectus abdominis muscles extend vertically from the pubic symphysis to the 5th to 7th costal cartilages

their contraction flexes the vertebral column, especially in the lumbar region.

Question 10

Discuss nerve innervation of the anterolateral abdominal wall.

Answer 10

somatic afferent fibers, somatic efferent fibers, and post-synaptic sympathetic fibers of intercostal nerves T5-T11, the subcostal nerve (T12), and the iliohypogastric and ilioinguinal nerves (L1) supply the anterolateral abdominal wall.

Question 11

Discuss the route taken by the abdominal aorta and its bifurcations.

Answer 11

the abdominal aorta bifurcates at vertebrae L4 (umbilicus is the surface indicator) into the right and left common iliac arteries that bifurcate into the external and internal iliac arteries.

Question 12

Discuss the route continuation of the external iliac artery and internal iliac artery.

Answer 12

external iliac artery continues as the femoral artery and the internal iliac artery enters the pelvic cavity

Question 13

Why does lack of muscle tone in the anterolateral wall contribute to visceroptosis and excessive lordosis?

Answer 13

Abdominal muscles protect and support the viscera most
effectively when they are well toned

When the anterior abdominal muscles are underdeveloped or become atrophic, as a result of
old age or insufficient exercise, they provide insufficient tonus to resist the increased weight of a protuberant abdomen on the anterior pelvis. The pelvis tilts anteriorly at the hip joints when standing (the pubis descends and the sacrum ascends) producing excessive lordosis (sway back) of the lumbar region.

Note: Visceroptosis is a condition in which the abdominal organs fall to a lower part of the abdomen.

Note: The six common causes of abdominal protrusion begin with the letter F: food, fluid, fat, feces, flatus, and fetus. Eversion of the umbilicus may be a sign of increased intra-abdominal pressure, usually resulting from ascites (abnormal accumulation of serous fluid in the peritoneal cavity), or a large mass (e.g., a tumor, a fetus, or an enlarged organ such as the liver).

Question 14

Why do palpation-induced spasms of the anterolateral wall muscles provide a clinical sign of acute abdomen?

Answer 14

Guarding- involuntary spasms of the abdominal muscles.

Intense guarding, board-like refl exive muscular rigidity that cannot be willfully suppressed, occurs during palpation when an organ (such as the appendix) is infl amed and in itself constitutes a clinically signifi cant sign of acute abdomen.

The involuntary muscular spasms attempt to protect the viscera from pressure, which is painful when an abdominal infection is present. The common nerve supply of the skin and muscles of the wall explains why these spasms occur.

Question 15

Discuss Camper’s fascia and what it is reinforced by.

Answer 15

fatty superficial fascia below the umbilicus is called Camper’s fascia that is reinforced by Scarpa’s fascia, a deep fascial layer formed by elastic and collagen fibers.

Question 16

Discuss lymphatic drainage of Camper’s fascia.

Answer 16

lymphatic vessels in Camper’s fascia drain into the superficial inguinal lymph nodes.

Question 17

Define the transversalis fascia what it lines.

Answer 17

endoabdominal fascia lines the internal surface of the musculotendinous sheet and is called the transversalis fascia where it lines the internal surface of the transverse abdominis.

Question 18

Discuss the relation of the EXTRAPERITONEAL FAT to transversalis fascia.

Answer 18

extraperitoneal fat separates the transversalis fascia from the parietal peritoneum (i.e., mesothelium analogous to the parietal pleura of the thoracic wall).

Question 19

What does the parietal peritoneum line?

Answer 19

parietal peritoneum lines the posterior aspect (internal surface) of the anterolateral abdominal wall.

Question 20

Discuss the formation of the falciform ligament and its function.

Answer 20

peritoneum reflects off the abdominal wall to from the falciform ligament (it separates the lobes of the liver)

Question 21

What forms the umbilical folds (3).

Answer 21

five narrow folds of the parietal peritoneum passing toward the umbilicus form the median, medial, and lateral umbilical folds.

Question 22

Inferior epigastric artery arises from which artery?

Answer 22

inferior epigastric artery arises from the external iliac artery

Question 23

Discuss the anastomoses of the inferior epigastric artery.

Answer 23

within the rectus sheath, the inferior epigastric artery anastomoses with the superior epigastric artery, a terminal branch of the internal thoracic artery.

Question 24

What forms the inguinal ligaments and discuss the ligament’s continuation (location).

Answer 24

the inferiormost part of the external oblique aponeurosis forms the inguinal ligament that extends from the ASIS to the pubic tubercle of the pubis.

Question 25

Discuss what forms the floor of the inguinal canal and the position of said (answer).

Answer 25

Inguinal ligament forms the floor of the inguinal canal that is just superior and parallel to the medial half of the ligament.

Question 26

Discuss the position of the superficial inguinal ring and the deep inguinal ring.

Answer 26

the superficial inguinal ring is superolateral to the pubic tubercle and the deep inguinal ring is superior to the midpoint of the inguinal ligament.

Question 27

Discuss the position of the deep inguinal ring to the INFERIOR EPIGASTRIC ARTERY (location).

Answer 27

Deep inguinal ring is lateral to the inferior epigastric artery.

Question 28

What forms the anterior/posterior wall of the inguinal canal.

Discuss in detail what makes up the latter.

Answer 28

Aponeurosis of the external oblique forms the anterior wall of the inguinal canal and the posterior wall is formed by the conjoint tendon (i.e., the merged aponeuroses of the internal oblique and transverse abdominis).

Question 29

In males the spermatic cord occupies (space).

Answer 29

Inguinal canal

Question 30

Discuss the route of the testis and attaches spermatic cord.

Answer 30

testis and attached spermatic cord traverse the deep inguinal ring

Question 31

Attached structures exiting the superficial inguinal ring are enroute to (structure).

Answer 31

Scrotum.

Question 32

Why does palpation of an impulse at the superficial inguinal ring and a mass at the deep inguinal ring define an indirect inguinal hernia? How can palpation distinguish a direct inguinal hernia?

Answer 32

The superficial inguinal ring is palpable superolateral to the pubic tubercle by invaginating the skin of the upper scrotum with the index finger. The examiner’s finger follows the spermatic cord superolaterally to the superficial inguinal ring. If the ring is dilated, it may admit the finger without causing pain.

Should a hernia be present, a sudden impulse is felt against either the tip or pad of the examining finger when the patient is asked to cough. However, because
both inguinal hernia types exit the superfi cial ring, palpation of an impulse at this site does not discriminate type.

With the palmar surface of the finger against the anterior
abdominal wall, the deep inguinal ring may be felt as a skin depression superior to the inguinal ligament, 2–4 cm superolateral to the pubic tubercle.

Detection of an impulse at the superficial ring and a mass at the site of the deep ring suggests an indirect hernia.

Palpation of a direct inguinal hernia is performed by placing the palmar surface of the index and/or middle finger over the inguinal triangle and asking the person to cough or bear down (strain). If a hernia is present, a forceful impulse is felt against the pad of the fi nger. The fi nger can also be placed in the superfi cial inguinal ring; if a direct hernia is present, a sudden impulse is felt medial to the finger when the person coughs or bears down.

Question 33

Where does an undescended testis commonly lie and what is its clinical risk? How is an undescended testis distinguished from an inguinal hernia in infants?

Answer 33

The undescended testis usually lies somewhere along the normal path of its prenatal descent, commonly
in the inguinal canal.

The importance of cryptorchidism is a
greatly increased risk for developing malignancy in the undescended testis, particularly problematic because it is not palpable and is not usually detected until cancer has progressed.

Note: If a testis has not descended or is not retractable (capable of being drawn down), the condition is cryptorchidism.

Question 34

Discuss the processus vaginalis (define formation and moving action).

Answer 34

Testis creates a diverticulum in the parietal peritoneum called the processus vaginalis that pushes the muscular and fascial layers of the anterolateral wall ahead of it through the deep inguinal ring.

Question 35

Define the formation of the internal spermatic fascia and what it surrounds.

Answer 35

Transversalis fascia forms the internal spermatic fascia that surrounds the processus vaginalis.

Question 36

What forms the cremaster muscle and cremasteric fascia. What does the cremaster muscle and cremasteric fascia surround?

What forms the external spermatic fascia? What does the external spermatic fascia surround?

Answer 36

Internal oblique and its aponeurosis form the cremaster muscle and cremasteric fascia that surround the internal spermatic fascia

Aponeurosis of the external oblique forms the external spermatic fascia that surrounds the cremaster and cremasteric fascia.

Question 37

Discuss the stalk portion and the distal saccular portion of the processus vaginalis.

Answer 37

Stalk portion of the processus vaginalis normally collapses around the spermatic cord and its distal saccular portion forms the tunica vaginalis that closely adheres to the testis and epididymis

Question 38

What nerve innervates the cremaster muscle?

Answer 38

Cremaster muscle is innervated by somatic efferent fibers of the genitofemoral nerve

Question 39

What nerve conveys sensations from the superomedial thigh?

Answer 39

Somatic afferent fibers of the ilioinguinal nerve convey sensations from the superomedial thigh.

Question 40

How is the cremasteric reflex tested?

Answer 40

Contraction of the cremaster muscle is elicited by
lightly stroking the skin on the medial aspect of the
superior part of the thigh with an applicator stick or tongue depressor.

Note: The ilioinguinal afferent nerve supplies this area of
skin. The rapid elevation of the testis on the same side is the cremasteric reflex.

Question 41

How is a persistent processus vaginalis related to a hydrocele of the testis, and how does a hydrocele of the testis differ from a hydrocele of the spermatic cord?

Answer 41

A hydrocele is the presence of excess fluid in a persistent
processus vaginalis.

The fluid accumulation results from secretion of an abnormal amount of serous fluid from the visceral layer of the tunica vaginalis. The size of the hydrocele depends on how much of the processus vaginalis persists.

A hydrocele of the testis is confi ned to the scrotum and
distends the tunica vaginalis.

A hydrocele of the spermatic cord is confi ned to the spermatic cord and distends the persistent part of the stalk of the processus vaginalis

Question 42

Discuss the route of the round ligament and interaction to other structures.

Answer 42

round ligament of the uterus extends from the lateral uterine wall through the inguinal canal into the subcutaneous tissue of the labia majora

Question 43

Are the PROCESSUS VAGINALIS and ROUND LIGAMENT less/more clinically relevant in women and why?

Answer 43

Processus vaginalis and round ligament normally become fibrotic; thus, the inguinal canal is less clinically relevant in females.

Question 44

Define indirect inguinal hernia.

Answer 44

Failure of the deep inguinal ring to close after the testis has passed through it during embryologic development. The hernia protrudes through the superficial inguinal ring. In an indirect inguinal hernia, the protrusion passes through the deep inguinal ring and is located LATERAL to the inferior epigastric artery. Hence, the conjoint tendon is not weakened.

Question 45

Define direct inguinal hernia.

Answer 45

The direct inguinal hernia enters through a weak point in the fascia of the abdominal wall, and its sac is noted to be medial to the inferior epigastric vessels.

A direct inguinal hernia protrudes through a weakened area in the transversalis fascia near the medial inguinal fossa within an anatomic region known as the inguinal or Hesselbach’s triangle, an area defined by the edge of the rectus abdominis muscle, the inguinal ligament and the inferior epigastric artery. These hernias are capable of exiting via the superficial inguinal ring and are unable to extend into the scrotum.

Note: Since the abdominal walls weaken with age, direct hernias tend to occur in the middle-aged and elderly. This is in contrast to indirect hernias which can occur at any age including the young, since their etiology includes a congenital component where the inguinal canal is left more patent (compared to individuals less susceptible to indirect hernias). Additional risk factors include chronic constipation, overweight/obesity, chronic cough, family history and prior episodes of direct inguinal hernias.

Question 46

median umbilical fold covers the fibrous remnant of the allantosis, the medial umbilical folds cover the occluded parts of the umbilical arteries, and the lateral umbilical folds cover the inferior epigastric arteries and veins.

Answer 46

a